Electric furnace.



J. A. HAY. I ELECTRIC FURNACE. APPLIOAT ION FILED JUNE 19, 1909.

Patented Alig. 31,1909.

IVE/WI? Jouu ALEXANDER HAY IT S ATas I m inmcan ELECTRIC FURNACE COMPANY,

JOHN a. HAY. or Lennon, ENGLAND, assrezwoa re A NEW roux, N. r, A coarona'r'ron or NEW l ST AVAILABLE coin stsecmrc FURNACE.

To all whom it may concern: I I a Be it known that I, JOHN A. Haigasubject of the King of Great Britain and Ireland, and residing at London, England, have invented a certain new and useful Im )rovement in Electric Furnaces, of which. the fol lowing is a specification. f i

My invention relates to electric furnaces and particularly to. electric furnaces of the induction type, the object of my invention being to provide improved meansfor cooling the primary or other winding surrounding the core. I In the accompan in drawings, Figural s a cross section of a furnace to which my invention is applied; Fi 2is a vertical section of the metallic shied drawn to a larger :aeal'e, and Fig. 3 is a sectiorrjon the line 33, I. 2. 1

in induction furnaces the vertical limb or limbs of the core with its primary or other coils ordinarily pierce the furnace and the coils are thus liable tobe subjected tothe injurious heat conducted through the walls of the crucible, or hearth. Various devices such as water 'ackets, asbestos linings and the like have con resorted to in order to protect the coils from injury by this heat relatively cool.

with more or less satisfactory results. 'A system of metallic shield-s through which is passed a currentof air has also been employed.

As a simple and yet efficient expedient I now propose to increase theradiating surface of the usual metallic shield A which lines tlje vertical passage through the furnace irg'which the limb or limbs of the transformer 'and coils (l are located, so that an air assagc will carry off the heat of the meta lic'shield A current flowing through this more readily and therefore maintain the limb or limbs of the transformer and coils While this increased radiation surface, may be obtained in various ways, I prefer to secure it by forming thin ribs B extcndiirg from top to bottom of the metallic shield. Were the ribs carried merely straight from top toflbottom, the radiating, surface of the metallic shield could be readily doubled. ButI propose to obtain a still further increase bymaking the ribs of grea'iter length than the axial diame- Speciflcation at Letters Patent. Application filed June 19, 1909. Serial No. 503,225.

ter of the metallic plate A.

shown this is accomplished byfmming In the examp the ribsspirally on the metallic shield, since the least opposition to the flow of the aircurrent is thus obtained. These spirally placed ribs also materially increase the strength of the metallic shield. v 1

The heat from the crucible is sullicicnl in and of itself to create an upward draft throu h the passage incloscd by the lining, and this in most cases is sullicient to keep the metallic shield A cooled, but this may be slupplemented by a forced draft, if de-' Sll8( For convenience of manufacture and to. facilitate the shaping of the hnmg to anv form of passage, the shield A may be made in sections as shown, two or more sections being joined by rivet plates E, and the divisions thus formed'being united byv dowel plates I) of insulating material.

Obviously my invention may be embodied in other forms of construction and I do not limit myself to the precise structure shown. but

I claim as my invention' 1. In an electric furnace having a passage through the crucible or hearth for limbs of the core and a Winding of the type described, a metallic shield for said passage having a radiation surface of materially greater area than the normal surface area of the passage.

2. In an electric furnace having a passage through the crucible or hearth for the limbs of the core and indings of the type described. a metallic shield for said passage having ribs formed thereon to increase the radiaiimi surface of said metallic shicld.

3. In an electric furnace having a passage through the crucible or hearth for the limbs Patented Aug. 31, 1909.

of the core and windings of the type described, a metallic shield for said passage having ribs of grealcr length than the axial diameter of said metallic shield. In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses.

JOHN A. IIAY. Witnesses:

Anoiru E. (lU'rosnLL, \VILLIAM ABBE. 

